1. Field of the Invention
The present invention pertains to an electronic apparatus and method for determining additional information about a patient's face, and, in particular, to an electronic apparatus and method for determining information on at least one of a location of hard tissue and tissue compliance in a patient's face.
2. Description of the Related Art
Obstructive sleep apnea (OSA) is a condition that affects millions of people from around the world. OSA is characterized by disturbances or cessation in breathing during sleep. OSA episodes result from partial or complete blockage of airflow during sleep that lasts at least 10 seconds and often as long as 1 to 2 minutes. In a given night, people with moderate to severe apnea may experience complete or partial breathing disruptions as high as 200-500 per night. Because their sleep is constantly disrupted, they are deprived of the restorative sleep necessary for efficient functioning of body and mind. This sleep disorder has also been linked with hypertension, depression, stroke, cardiac arrhythmias, myocardial infarction and other cardiovascular disorders. OSA also causes excessive tiredness.
Non-invasive ventilation and pressure support therapies involve the placement of a patient interface device, which is typically a nasal or nasal/oral mask, on the face of a patient to interface the ventilator or pressure support system with the airway of the patient so that a flow of breathing gas can be delivered from the pressure/flow generating device to the airway of the patient.
Typically, patient interface devices include a mask shell or frame having a cushion attached to the shell that contacts the surface of the patient. The mask shell and cushion are held in place by a headgear that wraps around the head of the patient. The mask and headgear form the patient interface assembly. A typical headgear includes flexible, adjustable straps that extend from the mask to attach the mask to the patient.
Because patient interface devices are typically worn for an extended period of time, a variety of concerns must be taken into consideration. For example, in providing CPAP to treat OSA, the patient normally wears the patient interface device all night long while he or she sleeps. One concern in such a situation is that the patient interface device is as comfortable as possible, otherwise the patient may avoid wearing the interface device, defeating the purpose of the prescribed pressure support therapy. Additionally, an improperly fitted mask can cause red marks or pressure sores on the face of the patient. Another concern is that an improperly fitted patient interface device can include gaps between the patient interface device and the patient that cause unwanted leakage and compromise the seal between the patient interface device and the patient. A properly fitted patient interface device should form a robust seal with the patient that does not break when the patient changes positions or when the patient interface device is subjected to external forces. Thus, it is desirable to properly fit the patient interface device to the patient.
3D scanning can be employed in order to improve the fit of the patient interface device to the patient. Generally, a 3D scan can be taken of the patient's face and then the information about the patient's face can be used to select the best fitting patient interface device or to custom make a patient interface device that fits the patient well. However, the 3D scan only includes information on the external geometry of the patient's face. The patient's face is more complex than its exterior geometry. For example, the patient's face has underlying hard tissue and various thicknesses of soft tissue in different areas in the face. These characteristics can affect how well a patient interface device fits.
Accordingly, a need exists for improvement in optimizing the fit of a patient interface device for a patient.